Displacement and Strain Field Measurement in Steel and RC Beams Using Particle Image Velocimetry

Conventional deformation measurement techniques, such as utilizing a LVDT, a demountable mechanical strain gauge (demec gauge), and an electrical strain gauge, despite their vast usage in experimental studies, suffer several disadvantages, including high cost, time-consuming specimen preparation, and the inability to obtain the whole displacement or strain fields. The aforementioned drawbacks on one hand and the importance of deformation measurements in all civil engineering laboratory tests on the other hand have led researchers to develop other measurement techniques, especially image-based techniques, capable of evaluating whole deformation fields. Among all of these recently developed methods, particle image velocimetry (PIV) has attracted much interest in all branches of civil engineering experimental investigations; PIV is a powerful image-based technique for evaluating both displacement and strain fields by analyzing successive digital images of a field undergoing deformation. Despite its great potential, however, few studies have been reported that use PIV for obtaining deformations for structural tests, especially for evaluating displacement and strain fields in a conventional bending test. Consequently, the intention of the current paper is to show the performance of the PIV technique for displacement and strain field measurement in bending tests of steel and RC beams subjected to four-point flexural loading. Based on different validation experiments of the current study, the PIV technique can be widely used as an alternative to conventional displacement and strain measurement techniques in bending tests. Moreover, the PIV technique demonstrated a great potential for investigating the fracture process in RC beams during the test process.